Separately, a Groupon spokesperson confirmed his departure, adding that Raj Ruparell, who has been in the sales organization for the past four months, will replace Brown.

When Brown joined Groupon in December 2010, Kara Swisher reported that he was considered a top-notch recruit from Yahoo.

But even before Brown joined the team, Groupon had some success in selling deals to both Nordstrom Rack and the Gap, which helped to raise awareness of the company and enlist new customers. But the number of high-profile promotions had started to dry up recently, with fewer and fewer offers gaining that kind of traction.

One source suggested that Brown’s departure was the result of Kal Raman, the newly appointed SVP, going through every department with a “fine-tooth comb” and cleaning house.

There have also been reports of staff departures in recent weeks. The Wall Street Journal reported this week that Jayna Cooke, another top salesperson at Groupon, had left the company.

Brown was credited with the creation of Groupon’s National Sales team, which arranges nationwide deals, rather than local offers.

“Under Lee’s management, the team has secured a number of key customers, and I’d like to personally thank Lee for his contributions and wish him the best in his next opportunity,” Raman wrote in the memo.